This invention relates to adhesive compositions for use on metal substrates, and particularly for use on copper leadframes within semiconductor packages.
Carboxyl benzotriazole is known as a good chelating material to copper metal. It is used not only as an antioxidant for metal substrates, but also as an adhesion promoter for epoxy resin pastes. Radical curing resins, such as acrylate or methacrylate esters, maleimide resins, vinylether resins and bismaleimide resins, for example, have been studied and applied for use in die attach adhesives in semiconductor packaging because of their low moisture absorption, ability to cure, and long pot life. However, these compositions are still deficient in providing good adhesion to copper lead frames.
This invention is an adhesive for use on metal substrates, and particularly on copper substrates, comprising (a) carboxyl benzotriazole, (b) an epoxy resin having a reactive double bond, (c) a radical curing resin, and (d) a radical initiator. The combination of elements (a) and (b) in a radical curing resin system composed of the elements (c) and (d) provides improved adhesion strength to copper metal compared to compositions containing (c) and (d) without (a) and (b).